The present invention relates to an image forming apparatus which causes a recording sheet on which a toner image has been transferred in an image forming section, to pass through an image fuser having a heating roller, thereby fixing the toner image on the recording sheet, and thereafter discharging the recording sheet to a discharge section by means of a discharge roller, and which has a duct, such as an exhaust air duct or a draft air duct. More particularly, the invention relates to an art for exhausting air from the inside of the image forming apparatus.
A related image forming apparatus includes an exhaust air duct for sucking air of a desired section within the apparatus and exhausting the air. Another related image forming apparatus include a draft air duct for blowing air to a desired section within the apparatus.
A related image forming apparatus in which, for the purpose of preventing a heating member from having inconsistent temperature distribution in its longitudinal direction, ribs are provided on a member covering an upper portion of the heating member along a direction crossing an air flow direction. The aperture areas of regions partitioned by the ribs are changed along the air flow direction (see, e.g., JP-A-07-234626).
A related image forming apparatus in which, for the purpose of suppressing temperature rise of a member which is disposed in the vicinity of the fuser and which may be accessed by a user's hand, without sacrificing fixing performance, the image forming apparatus is configured such that a recording medium on which an image has been formed, is subjected to fixing operation with use of a fuser, and the thermally-fixed recording medium is discharged to a discharge section disposed on an upper portion of the image forming apparatus; and is provided with a vent hole formed in a bottom portion arranged in the vicinity of an end portion of the discharge section located at a side of the fuser (see, e.g., JP-A-2003-186326).
When a recording sheet passes through a fuser to thus be heated, water vapor is emitted from the recording sheet. When a sheet guide, and the like, forming a transport path of the recording sheet are at a low temperature, condensation forms on the surface of the sheet guide, or the like. This condensation can stain the recording sheet, and hinder smooth transportation of the recording sheet.
The above-described related-art image forming apparatus is configured so as to exhaust air of only one side of the recording sheet having passed through the fuser. Accordingly, since water vapor on the other side of the recording sheet is not exhausted, condensation is formed on the surface of the sheet guide, and the like, which has led to staining of the recording sheet, and hindered smooth transportation of the recording sheet.
In the above-described related-art image forming apparatus, the aperture areas of the regions partitioned by the ribs in the duct are varied only by means of the air flow direction. Therefore, only a single air path communicating with the aperture areas is provided, and merely an end portion of the single air path opposes the fan. Rectification by means of the ribs is not attained. Accordingly, by means of such a configuration, a region of the fan where a suction force or a blast force provided by the fan is strong and a region where the same is weak cannot be utilized effectively, that is, effective exhaust is prevented.
In the above-described related-art image forming apparatus, one face of the duct is formed from a plate-shaped material. Accordingly, the apparatus has a problem in that the duct is increased in thickness, and, accordingly, in weight. Therefore, in a case where a duct is disposed in a door member (e.g., a door cover) of an image forming apparatus, there arises a problem in that the cover is increased in thickness, as well as in weight.